Traffic Data

Traffic flow on Britain’s roads: how to measure it and other information taken from surveying it.

You are here:

Speed surveys and the 85th percentile

The 85th percentile can be used to determine speed limits for roads. This is based on the theory that most drivers are reasonable and do not

Vehicle GPS data

The use of vehicle GPS data, or floating car data, is an emerging source of information that is becoming helpful in understanding traffic speeds and flows.

National Traffic estimates: An overview

Annual Average Daily Flow (AADF), or Annual Average Daily Traffic (AADT), refers to the average number of vehicles passing along a stretch of road in a

Rates and risk: what’s the difference

When comparing roads or areas that have substantial differences, looking at counts of collisions, casualties, or collision-involved drivers alone can give a misleading picture. For example, longer sections roads are more likely to have more collisions occur on them. Likewise, more heavily trafficked...